Illumination of gage or liquid-level glasses and the like.



L. G. WALKER.

ILLUMINATION 0F GAGE 0R LIQUID LEVEL GLASSES AND THE LIKE.

APPLlCATlON FILED JULY 20. 1917.

1,289,581 Patented Dec. 31, 1918.

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L. G. WALKER.

ILLUMINATION OF GAGE 0R LIQUID LEVEL GLASSES AND THE LIKE.

APPLICATION FILED JULY 20. 1917- 1,289,581 a I Patented Dec. 31, 1918.

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LAURENCE G. WALKER, 0F SUTTON, ENGLAND.

ILLUMINATION OF GAGE OR LIQUID-LEVEL GLASSES AND THE LIKE.

To all whom it may concern:

Be it known that I, LAURENCE GASTON l/VALKER, a subject of the King of Great Britain and Ireland, residing at Martlesham, Egmont Road, Sutton, Surrey, Eng land, have invented certain new and useful Improvements in the Illumination of Gage or' Liquid-Level Glasses and the like, of which the following is a specification.

This invention relates to the illumination of gage or level glasses and the like, and is particularly applicable to boiler water gage glasses, but the invention may also be applied to other similar apparatus, such for example, as spirit bubble level gages.

The object of the invention is to provide improved means whereby the height or position of the liquid column in the gage or level or an indication of it, shall be distinctly visible from a distance without causing visual strain or inconvenience to the observer, and without the necessity for close inspection, as required in the ordinary method of illuminating water level gage glasses.

In carrying out my invention in its preferred method, I utilize the optical properties of the gage glass and its contents in conjunction with a source of light, adapted to illuminate the gage glass, and a screen arranged in proximity to the gage glass, approximately at the focus thereof, so that owing to the lens actionv of the glass and its contents a bright line of light will be projected on to the screen by that part of the gage glass filled with liquid and which thus acts as a condensing lens of very short focus, While a diffused line or band will be projected on to the screen by the upper empty part of the glass, which acts as a difi'using lens, the line of demarcation, representing the top of the liquid column, being thus clearly apparent.

The principles employed are as follows 2- When the glass tube is partly filled with water or other transparent liquid the portion holding the water forms a short focus double convex or cylindrical lens, and if light from a suitable source is allowed to fall on the surface of the tube, a sharp brightly focused line image of the source of light will be formed on the screen, the upper end of the luminous line terminating sharply at the position coinciding with the top or end of the liquid column.

Specification of Letters Patent.

Patented Dec. at, 19118.

Applieaton filed .Tuly 20, 1917. Serial No. 181,923.

The empty portion of the tube acts as a concave lens and forms a very diffused image of the source.

The combined effect of the sharply focused bright image and the widely diffused image, produces a very distinct index, the dividing line of'which forms an immediate and substantially true indication of the height of the liquid column inthe gage glass tube.

It is to be stated that'in the methods hereinafter mentioned, the illuminant may consist of an electric lamp, tubular, or otherwise, or any other suitable light source, such as an incandescent gas burner, etc, also more than one source of light may be used. In cases where the'device can be arranged in a suitable position relatively to a window or the like, daylight can be employed as the light source. The light incident on the tube may be reflected light from a suitable surface which may be interposed to give the correct direction to the beam.

In some cases it may be desirable to have a colored image, in which case a color screen or screens may 'be interposed between the light and the viewingscreen or index.

I will now describe some Ways in which the invention may be carried out in practice.

Method 1: A. divergent, or parallel beam of light may be directed so as to pass through the cylindrical water gage glass, in such a way that the whole of the tube is covered by the beam. A ground glass or other screen may be placed in such a position approximately in the focal plane of the gageglass lens, as to receive a well defined pro ected bright band of light, and its dark attendant shadow band, formed by the liquid column, and also the diffused illumination produced by the upper empty portion of the tube. The screen or screens may be arranged edge-on to the side of the tube, or tangent thereto, the effect produced being that the edge or contacting surface of the screen cuts into the emerging beam of light; with the result that the line foci which converge very near to the perimeter of the tube, focus at or near the edge or part of the screen which is 1n contact or near to the tube surface, and since the screen cuts into the beam obliquely or at an angle the line foci. are extended to form a wider band of light than would be produced by a direct focus on a flat surface, that is, a surface at right angles'to the rays.

Thus the position and any variation in water level may be'at' once recognized by be used; also one .be used,,one on each side of thegage glass the screen.

When the source of light 1s placed some the position and variation in length of the bright luminous line or band index. In this method one or two sources of light may or two image screens may to receive the'pro'ected line foci, so as to be visible over a wi 0 angle of view.

According to a modification in the way of viewing the imagea totally reflecting prism or prisms maybe employed, the light passing through the gage glass tube being projected on to the surface of a totally reflecting prism or prisms andthence reflected to distance in front and below the gage glass tube, then light incident on the tube will pass through the liquid column and form a bright line focus on a screen, as already .described, but the oblique light incident at the critical angle on the surface of the liquid will be totally reflected, with the result that a dark shadow will be formed just above.

the bright line, thus producing a well defined index line, which is accentuated by the dark shadow, the light passing through the upper empty part of the .tube producing, as previously explained, abroad diffused image. y

Method 2: The gage glass may be illuminated from the back and a diffusing screen ner to produce a colored indication or dif-"' -ferent colored beams maybe directed above and below the normal water level to act as indicators.

I A lens or lenses may bdllsbd to condense the light fromc-t helight source so as toincrease its luminosity... I

For the purpose of renderin the image or indication still more noticeable, the lass tube may be partly darkened,'groun or rendered non-transparent where required, by painting or otherwise, and, in some cases, the scree'nmay be attached to or be part of the glass tube, or may beinthe formof a fluorescent screen.

In some cases I may employ in combinat1on w1th the ga e glass and screen in prox imity thereto, co ored or other indicators or level marks whereby the observer may readily see whether the water level is normal or approaching a higher or lower level.

'cator with means gage glass.

The invention will now be illustrated, by way of example, with reference to the accompanying drawings, in which ,Figure 1 represents in elevation partly n section on the line 11, Fig. 2, a strip indifor mounting it on the Fig. 2 bein a horizontal section, and Fig-"3 a si e elevation of Fig. 1. Fig. 4. is a view of a gage glass and screen illustrating the effect produced when the light is arranged at theside and approximately centrally of the glass.

Figs. 5 and 6 being cross sections on the lines 5- 5 and '6-6 respectively of Fig. 4.

Fi 7 illustrates-the effect produced when a di using screen is arranged in front of the ag]: glass and the light proceeds from the ac Figs. 8 and9 beingcross sections on the lines 88 and 9-9 respectively of Fig. 7.

Similar letters indicate like parts'througlrout the drawings.

Referring first to Figs. 4, .5 and 6, a repproximately centrally of the length of the gage glass, althou h the exact horizontal position ofthe light 1s not of great importance.

The eflfect produced on the screen I) will be as shown in Fig. 4:, the lower portion of the glass (1, condensing lens andbringing the image of the light to a focus at a point close to the perimeter of the tube. If the screen were arranged substantially at'right angles to the directlon of the rays of 1i ht andat the focal distance, a thin line of light would be projected on the screen, but in order to render the screenclearly visible and also toobtain a wider projection of light, the screen is arranged so that the plane of its surface forms a very wide angle with the rays of light and the focal line is thereforespread out, as it were, and is v sible in the form of a bright arts b, b of e light strip Figs. 5 and 6, adjai filled with liquid, acting as a I 25 feet, the actual water level is invisible toq the eye, or practically so, but the bright strip of light is very distinct, and gives an a diffusing screen I) is arranged in front of the gage glass a so that an image of the light line is focused on to the screen with an effect similar to that described in relation to Fig. 4.

In the arrangement illustrated in Figs. 4 to 9, the light is assumed to be more or less on a level with the top of the liquid in the gage glass. If the source of light is arranged below the gage glass, a slightly different efl'ect will be produced, the strip of bright light projected on to the screen will appear slightly higher than the actual liquid level, while immediately above it a section will appear which will be considerably darker than the' appearance of the upper part of the gage glass. This is due .to the fact that some of the light rays which strike upwardly against the top of the liquid column will be reflected and, consequently, will not pass through the liquid to illuminate the screen. i

A practical form of the invention embodying a screerrin proximity to a gage glass will now be described with reference to Figs. 1, 2 and 3.

a represents the ordinary gage glass se cured in place by the usual nuts a 03 is a rod, telescopic or otherwise, having reduced ends 01 upon which are mounted hinge members d capable of turning horizontally about said rod. These hinged members 03 are slotted at (Z Fig. 2, and their outer ends are bored to receive hinge pins 0, mounted on theholder b for the screen 2), which may be in the form of a piece of white card or opal glass, or a strip of material, colored or otherwise. These pins fit in the hinge mem bers d 'so that they can turn therein. A set screw (1 is provided in each member d for the purpose of locking the hinge member d both to the rod 03 and also to the pin 0, when the screen is placed in its adjusted position.

On the lower end 03 of the rod d is secured a horseshoe plate 0 havinga flange e on its underside, thus providing a recess in which a circular washer f on the tube 5 can be seated.

Asimilar plate 6 having a similar flange and recess is mounted on the upper end d of the rod (1 in such a way that it canmove up and down thereon. In the example illustrated the plate 6 has a projection 6 which is bored vertically to receive the end cl 0f the rod d, a vertical slot 6. being made in the projection e to'receive a pin (Z on the rod 0? to prevent lateral turning of the late 6 about d. Between the underside o the projection e and upper hinge, member d a spiral spring 9 is arranged, so as to press the plate upward and keep it in engagement with its washer f similarly to the lower plate 6.

As shown in Fig. 1, the space between the ends of the arms of each of the horseshoe plates is less than the diameter of the washer f, so that when the plates have been .engaged over the latter, the parts can only be disengaged by pressing downthe upper plate 6 against its spring 9 and then removing it with its rod and screen holder laterally.

By providing a double hinge construction as described, the screen can be very conveniently adjusted relatively to the gage glass, either nearer or farther from it, and also tangentially or at other angle thereto. F urther, owing to the double hinge arrangement, if necessary or desirable, the screen can be slightly shifted or set atan angle relatively to the gage glass instead of parallel therewith. When the screen has been adjusted into the desired position, it can be locked in place by tightening the screws (2.

While the above constitutes a convenient way of mounting the screen, it is to be understood that, in that respect, the inventlon is by no means limited to such arrangement, as the screen can be mounted" in any other way, with or without "capability of ad ustment, or it might be mounted directly on the gage glass itself or its connections.

As already stated my invention is based on the different effects produced by the optical properties of a gage glass partly filled with liquid, such effects being shown on a screen arranged approximately in the focal plane of the lens system so constituted. My invention, therefore, excludes the use of a mirror outsidethe'focal plane for merely reflecting an image of the gage glass to the observers eye, as the advantages obtained by my invention are not obtained by mere reflection. The efi'ect given by a mirror reflection will be no more distinct than that obtained by viewing the gage glass direct, whereas according to my invention the observer sees an intensified indication.

clearly focused. I

What I claim and desire to secure by Letters Patent 'is V 1. A method. of indicating the level of the liquid column inboiler gage glasses and the like, in which the optical properties of the I gage glass and its liquid contents are utilized, consisting in projecting light on to one side of the gage glass and. the arrangement of a screen on the other side thereof whereby contrasting light efl'ects are produced on the screen corresponding to the height of the liquid in the gage glass owing, on the one hand, to the presence of liquid in one portion of the tube, and, on the other hand, to absenceof liquid from the other portion of said tube.

2. liquid column in boiler gage glasses and the like, in which the optical properties of the gage glass and its contents are utilized as a lens, consisting in projecting light by means of the gage glass on to a screen or the like arranged a proximately in the focal plane of the lens ormed by the gage glass and its liquid contents, so -asto produce a bright indlcating line or strip on the screen corresponding tothe height of the liquid in the gage glass, .while the upper part of the gage glass above the liquid level, acting as a diffusing lens, produces a contrasting light effecton the upper part of the screen. i

3. For carrymg out the method of indicating the level of the liquid column in boiler -,qage glasses and the like, as set forth in A method of indicating the level of the plane of the lens ormed by the gage glass and its liquid contents, said screen being arranged with the plane of its surface forming a wide angle with the rays from the light source, for the purpose described; 1 I 4. A gage glass indicator comprising a gage glass, 7 ga'geglass in a plane parallel to the longitudinal plane of the gage glass, and means for adjusting the screen toward or from the gage lass and tangentially to the gage glass. 5. g gage glass indicator comprising a gage glass, a screen arranged laterally of the gage glass and in a plane parallel to the longitudinal plane thereof, means for adjusting the screen toward or from and tangentially to the gage glass, a carrier for said screen, a hinge connection between the screen and carrier and means for removably securing said carrier to the gage glass mounting.

In testimony whereof I have affixed my signature in presence of two witnesses. LAURENCE G. Witnesses:

MARGUERITE M, KROBER, I STANLEY G. S." DIGKER.

a screen mounted laterally of the 

